Bath regulator for dense media separation systems



Sept. 6, 1955 c, LEV] 2,717,079

BATH REGULATOR FOR DENSE MEDIA SEPARATION SYSTEMS Filed April 1, 1954 2 Sheets-Sheet l 70 BAT/f INVEN TOR. BY $055 5 Z 601/,

Sept. 6, 1955 C. B. LEVI BATH REGULATOR FOR DENSE MEDIA SEPARATION SYSTEMS 2 Sheets-Sheet 2 Filed April 1, 1954 INVENTOR. C056 ,5 [61/0,

United States PatentO BATH REGULATOR FOR DENSE MEDIA SEPARATION SYSTEMS Cass B. Levi, Pittsburg, Kans., assignor to The McNally Pittsburg Manufacturing Corporation, Pittsburg, Kans., a corporation of Kansas Application April 1, 1954, Serial No. 420,336

7 Claims. (Cl. 209 172.5)

The invention relates to the art of gravity separation of solid materials by means of an aqueous suspension of fine solid particles comprising the bath medium and has reference more particularly to the provision of improved apparatus for automatically maintaining the bath medium of such gravity separation system at the particular desired density. I

The separation of solid materials having different specific gravities by means of an aqueous suspension of fine solid particles has been employed in the cleaning of coal by separating the coal which floats in the'suspension bath from the accompanying impuritieswhich sink to the bottom of the bath. The invention-is especially applicable to a system wherein the suspension bath is maintained at a specific gravity which is greater than the float solids but less than that of the sink solids and wherein the bath medium comprises finely divided solids such as magnetite and water. I

When two or more baths, particularly, if separating at diflerent densities, are used in connection with a common recovery circuit, a bath regulator is generally provided for each bath. As a result, the recovery regulator is only required to control the recovered medium at approximately the maximum density desired for the baths. The bath regulators dilute or thicken the medium to the proper density for their respective baths and are also capable of compensating for any extraneous moisture entering the bath or bath circuit. 7

Accordingly, an object of the invention is to provide an improved bath regulator for controlling the density of the bath medium, which will be eflicient and positive in operation, and wherein the density of the bath medium delivered to the bath will be regulated automatically by means of a continuous testing hydrometer and mechanism actuated thereby.

Another object of the invention resides in the provision of a bath regulator which will continuously test the density of the medium recirculating in the bath circuit, and which will correct the density thereof, if too high, by movement of a diverting gate to add clarified water, and if the density is too low, will eflect movement of the gate to discharge from the system the overflow from the classifying cone whereby to cause a withdrawal of liquid from the bath medium rather than an addition of solid particles.

Another object is to providea bathregulator for a dense media separation system wherein a positioning motor is provided for actuating the diverting gate to in' turn regulate the density of the bath medium, and wherein the positioning motor is controlled through electrical means from a balance beamhaving movement in accordance with changes in density of the bath medium 'as detectedby a continuously testing hydrometer.

A further object is to provide time delay mechanism in combination with the electrical positioning motor for delaying actuation of the motor for a predetermined period of'time'before introducing clarified water, whereby to prevent dilution of the bath circuit due to momentary 2,717,079 Patented Septr 6, 1955 fluctuations in the specific gravity of the bath medium as detected by the testing hydrometer.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the device and wherein like reference characters are used to designate like parts- I Figure l is a view schematically illustrating a preferred embodiment of the bath regulator of the invention;

Figure 2 is a perspective view of the electric positioning motor employed for effecting actuation of the diverting gate, the said view clearly showing the tripper arm and clutch on the armature shaft; f

Figure 3 is a wiring diagram schematically illustrating the circuit elements of the time delay mechanism, the tripper arm being shown in an inoperative position relative to the time delay mechanism with the micro-switches open; and

Figure 4 is a view similar to Figure 3 but showing the tripper arm in an operative position with the microswitches closed, but with the-time delay unit in position to effect time delay when the positioning motor attempts dilution of the circuit.

Referring to the drawings, and particularly Figure l, the pipe 10 has connection with the bath circuit of a dense media separation system and functions to continuously. divert some of the bath medium to the classifying cone generally designated by numeral 11. The classifier cone functions to separate the bath medium into two portions, one of which may be referred to as the dilute overflow and the other as the thickened underflow. The overflow launder 12 is associated with the top edge of the classifier cone and the launder functions to collect the overflow and deliver the same through pipe 13 to the diverting gate enclosure or regulator 14. The thickened underflow is withdrawn from the bottom of-the classifier cone through valve 15 which is positioned directly above a funnelshaped receiver 16 connected with pipe 17, having connection with the four-way union 18. By the setting action taking place in the classifier cone a continuous por tion of thebath medium is divided into an underflow of concentrated medium which is returned to the bath circuit, and into an overflow of dilute medium which is delivered to the regulator and which may be diverted out of the circuit or returned to the circuit, depending on the action of the continuous testing hydrometer, whichstructure will now be described.

From the four-way union the bath medium delivered thereto is delivered by pipe 20 to a recirculating sump indicated by numeral 21. The sump comprises a container in the general shape of a cone and has a single outlet at the base orapex thereof as represented by pipe 22, the. same leading to a motor operated pump 23 having its outlet connected to the delivery pipe 24. From the delivery pipe 24 the bath medium takes three different courses. pipe 25 which returns the medium to the bath. A minor portion is diverted by pipe 26 and this portion-is returned to the classifier cone. Another minor portion is diverted through pipe 27, which delivers the same to the testing vessel 28 containing the hydrometer 30. The testing vessel is substantially cylindrical in shape, having'an opening at the top through which rod 29 extends for suspending the hydrometer from the left hand end of the balance beam 32. Adjacent the open end of said vessel there isprovided an overflow pipe 31. The bottom of the testing vessel is provided with an outlet orifice 33 positioned directly above a funnel-shaped receiver 34 which is connected with overflow pipe 31 and with pipe 35 lead The major portion of the same is delivered to ing to the four-way union 18. The outlet orifice 33 presents an orifice of fixed size through which the medium leaves the testing vessel, thus preventing thickening of the medium in the vessel and at the same time continuously presenting new medium for testing. The overflow pipe 31 maintains the medium in the vessel at a constant level. It will be understood that bath medium is continuously delivered to the testing vessel so that the hydrometer is continuously testing the density of the medium being returned to the bath.

The hydrometer bulb 30 through its connecting rod 29 may have a knife edge connection as at 36 with the balance beam 32, which is pivotally supported at an intermediate point by means of a pair of suitable ball bearings 37, which are supported by standards such as 38. 'The beam is counterbalanced on that side of the pivot opposite the hydrometer bulb by an adjustable member 40 which may be located in various adjusted positions along the beam in order to select the particular specific gravity as may be desired for the bath medium. Thus, for any given setting the vertical position of hydrometer 30 responds to the density of the medium in the testing vessel. A secondary adjustment on the balance beam may be provided in order to compensate for the effects of the vertical flow past the surface of the bulb.

A soft iron core 41 is fixed to the right hand end of the balance beam, the same being disposed vertically at right angles to the beam. The respective ends of the soft iron core 41 are adapted to have location within electrical inductance coils 42 and 43, one being located above the beam and the other being located below the beam so that as the hydrometer may effect pivotal movement of the beam, due to variations in the density of the bath medium, either above or below the desired density, the iron core 41 is caused to enter one electrical coil and leave the other. Coils 42 and 43 are connectedby means of conductors .44, 45 and 46 to a positioning motor indicated in its entirety by numeral 48. Movement of the iron core within the induction coils, will change the flux intensity and vary the impedance, or apparent resistance, of the coils, increasing one and decreasing the other. Said conductors connect with a variable resistance in the positioning motor 48 in such manner that as the impedance of the coils is changed the motor armature is rotated until both sides of the variable resistance in the motor balances the changed resistance in the two coils. The armature of the positioning motor 48 is thus rotated and it will be understood that the position of said armature is infinitely variable within its angular range. A positioning motor such as disclosed and claimed in the Edmondson Patent 2,127,680 of August 23, 1938, has been found completely satisfactory for the purposes of the present invention.

As best shown in Figure 2, the armature shaft 50 of the positioning motor 48 has the crank arm 51 fixed to one end thereof and said shaft has the tripper member 52 fixed to the opposite end. A friction type clutch 53 is located on the armature shaft, being interposed between the shaft and the tripper arm 52. The crank arm 51 is connected through suitable linkage such as 54 with the diverting gate 55, being pivotally supported at 56 within the diverting gate enclosure or regulator 14 and functioning in a manner to divide the enclosure into two compartments, the left hand compartment being supplied with clarified water from the pipe 57 and the right hand compartment being supplied by pipe 13 with the dilute overflow from the classifier cone. Said compartments also have their own outlet, the left hand compartment having connection with outlet 58 leading to the dilute medium sump of the recovery system and the right hand compart ment connecting with outlet 59 having connection with four-way union 18 for return to the bath circuit.

Should the armature shaft 50 of the positioning motor rotate in a clockwise direction, Figure 1, it will be seen that the crank arm 51 and linkage 54 will efiect counterclockwise rotation of the diverting gate 55 which locates n 4 the upper end of the diverting gate toward the clarifie water inlet for decreasing the density of the bath medium. When the diverting gate is so positioned it operates to divert varying amounts of clarified water to the bath, the said clarified Water being directed into the right hand compartment of the regulator so that the liquid is discharged into the recirculating sump 21 and is thus mixed with the bath medium to dilute the same. When the armature shaft of the positioning motor rotates counter-clockwise, Figure 1, the action of the crank arm and linkage is such as to rotate the diverting gate 55 in a clockwise direction, and as a result the upper end of the diverting gate is positioned toward the overflow inlet for increasing the density of the bath medium. The density of the bath. medium is increased since varying amounts of the dilute overflow from the classifier cone, is diverted out of the circuit by being discharged through outlet 58 to the dilute medium sump. When the bath medium is regulated to the correct density the diverting gate 55 is positioned in a vertical or neutral position, in which position of the gate it will be seen that clarified water will be discharged to outlet 58" and diverted out of the circuit, andthat the dilute overflow will be discharged tooutlet 59 and is thus directed back to the bath medium, causing no change in the density of the medium. In accordance with the invention, the bath density is increased or decreased without the addition of outside fresh water to the medium or without adding suspension media irr -the form of fine solid particles. Rotation of the armature shaft of the positioning motor is of course eifected through electrical means including the inductance coils 42 and 43 which are influenced by movement of the iron core 41, caused by movement of thecontinuous testing hydrometer bulb 30. As a result of the electrical connections between the coils and the posi tioning motor, it will be understood that the hydrometer bulb and beam are not required to do any work other than overcome the negligible friction of the pivot bearings. This accounts in a large measure for the extreme accuracy of the present bath regulator.

In order to prevent dilution of the-bath medium due to momentary fluctuations in the specific gravity of the medium as detected by the hydrometer, the invention incorporates time delay mechanism such as 60 in the motor circuit of the positioning motor. Some momentary gravity fluctuationsi-n the bath medium are sometimes encountered when the recovery coneregulator diverts a particularly heavy concentration of magnetite to the bath circuit. The purpose of the time delaymechanism' is to cause the positioning motorto Wait a predetermined timebefore introducing clarified water for decreasing the den sity. Thus, when the hydrometer indicates that the mediumis heavy, the time delay mechanism eifects a delay equal to the time necessary for the medium to make a complete circuit through the recirculating pump 23 and the bath. If the medium continues to register heavy, the positioning motor is permitted to make the correctionby introducing clarified water until the medium is reduced to the desired operating density. In the event the bath medium is light and it is necessary to divert the dilute overflow in order to increase the density of the medium, the time delay mechanism is not involved and the positioning motor is free to operate-immediately to effect the required thickening operation.

The circuit elements and-connections there'for comprising the time delay mechanism are shown in various operative positions in Figures 3 and 4.. The power supply, indicated by leads L1 and L2, is electrically connected in series circuit relation with a time delay unit 61, andv said leads additionally connect with terminals 62 and 63.

The unit 61 may comprise the conventional type of time delay device employing some form of electrical means which upon energization will eifect a lifting of the contactor 64 to its elevated position. Upon deenergization either a mechanical or an electrical time delay becomes operative for delayin'g'rel'e'ase" and downward movement of the contactor. In down position the contactor 64 electrically connects terminals 65 and 66. In a similar manner when said contactor is in an up position itelectrically connects terminals 67 and 68. The terminals 66 and 68 are connected by means of the branch conductor 70 to lead L2. Another branch conductor, indicated by numeral 71, connects terminal 63 with terminal 65, the said conductor joining the primary winding 72 in series relation with said terminals. Primary winding 72 constitutes part of the transformer 73, having secondary winding 74, the respective terminals of which are connected to the positioning motor 48 as at 75 and 76. The terminals 62 and 63 in combination with the pivoted contact 78 constitutes a micro-switch which is actuated by arm 80 of the tripper member 52. The arm 81 of tripper member 52 actuates the pivoted contact 82 of a second micro-switch associated with terminals 83 and 84. The contact 78 has pivotal movement on terminal 62 as an axis and said contact is yieldingly held in an open position by coil spring 85. In a similar manner contact 82 has pivotal movement on terminal 83 as an axis and the contact is held in open position by coil spring 86.

As shown in Figure 3, the tripper member is positioned horizontally so that the arms 80 and 81 thereof permit the movable contacts 78 and 82 to assume an open position. In this position of the micro-switches the solenoid of unit 61 is deenergized so that the contactor 64 drops into its down position to close the terminals 65 and 66.- As a result a circuit is established from lead L1 tolead L2 through the primary winding 72 so that the winding is energized and current is supplied to the positioning motor. The motor is accordingly operative and any movement of the balance beam will be reflected in similar movement of shaft 50 of the positioning motor.

When it becomes necessary to thicken the bath medium, the shaft 50 of the motor will be rotated clockwise, Figure 3, as previously explained, and eventually the microswitches will be closed by clockwise movement of the tripper member 52. Since the tripper member 52 is driven through the friction clutch 53 the motor continues to operate to effect a thickening of the bath medium although the tripper member is held against rotation as a result of arms 80 and 81 which hold the movable contacts 78 and 82 against terminals 63 and 84, respectively. This position of the parts is shown in Figure 4 and it will be observed that closing of the two micro-switches has energized the unit 61 to locate the contactor 64 in its up position. Thus a circuit is completed by the contactor 64 and the movable contact 82 through the primary winding 72.

After the required correction has been made in the density of the bath medium the hydrometer bulb will move to terminate the thickening operation. Such movement of the bulb is reflected in counterclockwise rotation of the tripper member 52 and immediately thereafter the microswitches will be opened, thus breaking the circuit and deenergizing primary winding 72. Accordingly, when the motor starts to reverse following a thickening operation the circuit through primary winding 72, and including contactor 64, is opened to discontinue the supply of electrical energy to the motor. The time delay unit 61 now becomes operative and the same may be set to efiect a time delay of from two seconds to two hundred seconds. As previously explained, the delay is set so as to be substantially equal to the time necessary for the bath medium to make a complete circuit through the recirculating pump and bath. When this time has elapsed the unit 61 allows the contactor to descend into its down position. Accordingly, the electrical circuit through primary winding 72 is reestablished and the motor becomes operative again to position the diverting gate. Thus should the bath medium continue to register heavy, the motor will continue to operate to locate the diverting gate 55 for introducing clarified liquid to the bath medium and this operation will continue until the medium is desired operating gravity.

During the time the present apparatus may be shut down or idle for some reason, the bath medium will drain 'back to the medium storage sump. Consequently the medium is drained from the testing vessel 21 so that without the buoyancy of the medium the hydrometer 30 will drop to a position which calls for thickening of the medium, regardless of the actual density of the' medium contained in the medium storage sump. Thus, when the medium is again pumped back to the bath and to the testing vessel, the tripper member 52 assumes the position as shown in Figure 4 and the member is thus in position to effect a, time delay before a decreasing of the density of the medium takes place.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings, as various other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

What is claimed is:

1. In apparatus for regulating the density of a ba medium comprising ultra-fine solids in water, the combination including a testing vessel having a fixed outlet orifice and an overflow, a balance beam, an hydrometer suspended from one end of the balance beam and having location in the testing vessel, means continuously supplying bath medium to the testing vessel to submerge reduced to the the hydrometer and effect movement of the balance beam" as the density of the bath medium may vary, a pair of inductance coils associated with the other end of the balance beam in a manner causing a balanced condition as regards the impedance of the coils when the beam is disposed in a horizontal neutral position and an unbalanced condition when the beam is above orbelow said horizontal position, a regulator to which is separately supplied a dilute. medium and clarified water, a positionable diverting gate within the regulator for controlling the density of the bath medium by controlling'flow of the dilute medium and the clarified water, whereby the liquids may be delivered to the bath medium or diverted from the system, said gate having a first operative position for increasing the density of the bath mediumby'.

diverting both liquids from the system, said 'gate having a second operative position for decreasing the density of the bath medium by delivering both liquids to the bath medium, and said gate in a neutral position returning the dilute medium to the bath medium but diverting the clarified water out of the system, and an electric positioning motor responsive to the balanced and unbalanced conditions of said inductance coils for actuating the diverting gate.

2. Apparatus for regulating the density of a bath medium as defined by claim 1, additionally including time delay mechanism in association with the positioning motor for delaying operation of the motor for a predetermined time under conditions calling for a decrease in density whereby to prevent minor fluctuations in the bath density from effecting actuation of the diverting gate in a direction to decrease the density.

'3. In apparatus for automatically regulating the density of a bath medium comprising ultra-fine solids in water, the combination including a testing vessel, a balance beam, an hydrometer suspended from one end of the balance beam and having location in the testing vessel, a classifier cone, means discharging bath medium into said cone and which by a settling action divides the same into a dilute overflow portion and a thickened underflow portion, conduit means for returning said thickened V underflow to the bath circuit, a regulator to which the dilute overflow is delivered, means for delivering clarified water to the regulator, a positionable diverting gate in the regulator for regulating the density of the bath medium, second conduit means for continuously delivering a minor portion of the returning bath medium to the testing vessel to submerge the hydrometer and effect movement of the balance beam as the density of the bath medium may vary, a pair of inductance coils associated with the other end of the balance beam in a manner whereby to eifect a balanced or an unbalanced condition ofthe coils as regards their impedance due to movement of the beam, and an electric positioning motor responsive to the balanced or unbalanced conditions of the inductance coils for actuating said diverting gate.

4. Apparatus for automatically regulating the density of a bath medium as defined by claim 3, additionally including time delay mechanism in association with the positioning motor for delaying actuation of the motor for a predetermined time in those instances when the hydrometer moves to decrease the bath density, whereby minor fluctuations in the bath density are prevented from effecting actuation of the diverting gate for decreasing the density of the bath medium.

5. In apparatus for regulating the density of a bath medium comprising ultra-fine solids in water, the combination including a source of supply of said bath medium, a classifier cone receiving the bath medium from said supply source, said cone by a settling action dividing the bath medium into a dilute overflow portion and a thickened underflow portion, a regulator, a supply pipe for delivering said dilute overflow portion to the regulator, a clarified water supply pipe also connecting with the regulator, said regulator having a positionable diverting gate for regulating the density of the bath medium, said gate in one angular position adding clarified water to the dilute overflow and mixing the overflow as thus diluted with the thickened underflow for return to the bath circuit, said gate in another angular position diverting both the clarified water and the dilute overflow so that only the thickened underflow is returned to the bath circuit, and said gate in a neutral position diverting the clarified water but mixing the dilute overflow with the thickened underflow so that the density of the bath medium as it is returned remains the same, a testing vessel to which a minor portion of the recirculating bath medium is continuously delivered, a balance beam, an hydrometer suspended from one end of the balance beam and located in the testing vessel for vertical movement as the density of the bath medium may vary, a pair of inductance coils associated with the other end of the balance beam in a manner whereby the impedance of the coils is balanced when the beam is above or below said horizontal neutral position, and an electric positioning motor responsive to the balanced and unbalanced conditions of said inductance coils for actuating said diverting gate;

vented from effecting actuation of the diverting gate for decreasing the bath density.

7, In apparatus for regulating the density of a bath medium, the combination of a classifier cone and means delivering bath medium thereto, said cone by a settling action dividing the bath medium into a dilute overflow portion and a thickened underflow portion, a regulator to which is separately supplied the dilute overflow and clarified water, said regulatorhaving a positionable diverting gatewhich in neutral position recombines the dilute overflow with the thickened underflow for return to the bath circuit, which in a first operative position diverts the dilute overflow from the system to increase the bath density, and in a second operative position adds the clarified water to the dilute overflow and recombines the overflow as thus diluted with the thickened underflow to decrease the bathdensity, hydrometer means for testing the density of the bath medium being returned to the bath circuit, an electricpositioning motor having operative connection with the diverting gate for actuating the gate, electricconnections beween the hydrometer means and motor for effecting rotation of the motor in accordance with variations in the bath density as detected by the hydrom eter means, an electrical time delay mechanism in associatedrelation with the positioning motor, said time delay mechanism when operative delaying operation of the positioning motor for a predetermined time, and means rotated by the positioning motor for rendering the time delay mechanism operative under those conditions when, following a period wherein the bath density is increased, the hydrometer means calls for a decrease in the bath density.

References Cited in the file of this patent UNITED STATES PATENTS 2,320,519 Hirst June 1, 1943 

1. IN APPARATUS FOR REGULATING THE DENSITY OF A BATH MEDIUM COMPRISING ULTRA-FINE SOLIDS IN WATER, THE COMBINATION INCLUDING A TESTING VESSEL HAVING A FIXED OUTLET ORIFICE AND AN OVERFLOW, A BALANCE BEAM, A HYDROMETER SUSPENDED FROM ONE END OF THE BALANCE BEAM AND HAVING LOCATION IN THE TESTING VESSEL, MEANS CONTINUOUSLY SUPPLYING BATH MEDIUM TO THE TESTING VESSEL TO SUBMERG THE HYDROMETER AND EFFECT MOVEMENT OF THE BALANCE BEAM AS THE DENSITY OF THE BATH MEDIUM MAY VARY, A PAIR OF INDUCTANCE COILS ASSOCIATED WITH THE OTHER END OF THE BALANCE BEAM IN A MANNER CAUSING A BALANCED CONDITION AS REGARDS THE IMPEDANCE OF THE COILS WHEN THE BEAM IS DISPOSED IN A HORIZONTAL NEUTRAL POSITION AND AN UNBALANCED CONDITION WHEN THE BEAM IS ABOVE OR BELOW SAID HORIZONTAL POSITION, A REGULATOR TO WHICH IS SEPARATELY SUPPLIED A DILUTE MEDIUM AND CLARIFIED WATER, A POSITIONABLE DIVERTING GATE WITHIN THE REGULATOR FOR CONTROLLING THE DENSITY OF THE BATH MEDIUM BY CONTROLLING FLOW OF THE DILUTE MEDIUM AND A CLARIFIED WATER, WHEREBY THE LIQUIDS MAY BE DELIVERED TO THE BATH MEDIUM OR DIVERTED FROM THE SYSTEM, SAID GATE HAVING A FIRST OPERATIVE POSITION FOR INCREASING THE DENSITY OF THE BATH MEDIUM BY DIVERTING BOTH LIQUIDS FROM THE SYSTEM, SAID GATE HAVING A SECOND OPERATIVE POSITION FOR DECREASING THE DENSITY OF THE BATH MEDIUM BY DELIVERING BOTH LIQUIDS TO THE BATH MEDIUM, AND SAID GATE IN A NEUTRAL POSITION RETURNING THE DILUTE MEDIUM TO THE BATH MEDIUM BUT DIVERTING THE CLARIFED WATER OUT OF THE SYSTEM, AND AN ELECTRIC POSITIONING MOTOR RESPONSIVE TO THE BALANCE AND UNBALANCED CONDITIONS OF SAID INDUCTANCE COILS FOR ACTUATING THE DIVERTING GATE. 